Renovation words explained

A device in the consumer unit that switches off a circuit when it detects arcing: small sparks from a damaged cable or a loose connection, which can start a fire. It does a different job from an RCD, which protects people from electric shock. Ask your electrician whether your circuits should have them and whether the quote includes them.

The old name for a registered building control approver: a private inspector you can choose instead of the council to check that building work meets the building regulations in England and Wales. They were renamed on 6 April 2024, but quotes still use the old name. If a quote says building control is by an approved inspector, ask whether their fee is in the price.

Sources: SI 2024/104 for England, SI 2024/207 for Wales.

An order by your council that removes some or all permitted development rights in an area, often a conservation area, so work that would normally need no application does. Ask the council’s planning department whether one covers your street.

Source: Planning Portal.

The posts and handrail along the open side of a staircase or landing, which stop anyone falling. A new loft staircase needs one.

A checklist the installer fills in, usually at the back of the instruction manual, when a new boiler or hot water cylinder is set up, recording that it was installed and commissioned properly. Keep it: manufacturers ask for it if you make a warranty claim.

A government grant in England and Wales towards replacing gas, oil, LPG or electric heating with a heat pump or a biomass boiler. It pays £7,500 towards an air source heat pump. Until 31 March 2027, a home heated by oil or LPG with no mains gas gets £9,000 (£1,500 more). An air-to-air heat pump gets £2,500. Your MCS certified installer applies for it on your behalf.

Sources: GOV.UK, what you can get.

The legal line between your land and your neighbour’s. In England and Wales the title plan from HM Land Registry gives an idea of where it runs, but most title plans don’t show the exact line. Building close to it can bring in planning limits and party wall notices.

Source: GOV.UK.

Permission from your water company to build over, or close to, a public sewer, for example when an extension covers a drain shared with neighbours. Building control checks for it under the building regulations in England and Wales. Ask early, because it can hold up the start.

Source: Approved Document H, requirement H4.

The service that checks building work meets the building regulations: your council’s building control team, or a private registered building control approver you choose instead (England and Wales). They inspect the work at key stages and issue the completion certificate.

Scotland: In Scotland the council’s building standards department (the verifier) does this job, through the building warrant; there are no private inspectors. (mygov.scot)

Source: GOV.UK.

A quicker way to get building regulations approval for smaller jobs in England and Wales: you tell building control about the work and can start 2 days later. No plans are approved in advance, so anything the inspector finds wrong has to be put right on site.

Source: GOV.UK.

The legal minimum standards for building work, covering structure, fire safety, insulation, drainage, electrics and more. They are separate from planning permission: most extensions, loft conversions and structural changes need building regulations approval even when no planning application is needed. Northern Ireland has its own regulations, approved by your district council’s building control.

Scotland: Scotland has its own building regulations (building standards). You need a building warrant before work starts and must submit a completion certificate at the end. (mygov.scot)

Source: GOV.UK.

Legal permission from your council’s building standards department to carry out building work in Scotland, such as an extension, a loft or garage conversion, or altering a load-bearing wall. You must have it before work starts, and it lasts 3 years.

Source: mygov.scot.

Wording on a quote that means the item is not included: someone else, often you, has to supply it or arrange it. Add it to your budget separately.

The formal name for a lawful development certificate. In Scotland you apply to the council for a certificate of lawfulness of proposed use or development to confirm that planned work doesn’t need planning permission.

Source: Town and Country Planning (Scotland) Act 1997, section 151.

Grooves cut into a wall or floor to bury new cables or pipes, which are filled and plastered over afterwards.

A combination boiler heats water straight from the mains when you turn on a hot tap, so there is no hot water cylinder or tank in the loft. It suits homes where one shower runs at a time.

A government-approved scheme for tradespeople, such as electricians and heating engineers, that lets a registered installer certify their own work as meeting the building regulations. You then don’t need to apply to building control yourself for that work (England and Wales).

Source: GOV.UK.

In England and Wales, the certificate building control issues when it is satisfied the finished work meets the building regulations, usually within 8 weeks. Keep it: a buyer’s solicitor will ask for it when you sell. Hold back the final payment until it is issued.

Scotland: It works the other way round in Scotland: you (or your agent) submit a completion certificate to the council when the work is finished, and the council accepts it if the work meets the building warrant and Scotland’s building standards. It is an offence to move into a new extension before it has been accepted. (Scottish Government procedural handbook, chapter 5)

Source: GOV.UK.

An area your council protects for its special architectural or historic character. Permitted development is narrower there: in England, for example, side extensions and cladding need planning permission. To find out whether your home is in one, ask your council’s planning department.

Source: Planning Portal.

The box, usually near the electricity meter, where the supply is split into separate circuits, each with its own switch that cuts off if something goes wrong. Also called a fuse board. Fitting a new one must be notified under the building regulations in England and Wales.

Source: Planning Portal.

Money you set aside for things nobody can see or price until work starts, such as rotten timbers or poor ground. It is an allowance, not a cost: if nothing goes wrong, you keep it. Estiquote’s budgets hold 15% of the building work (10% for a boiler, unvented cylinder replacement, a heat pump or windows, which are usually fixed prices).

A box-shaped extension built out from a sloping roof, with its own window, to give standing room in a loft. A rear dormer is the most common loft conversion.

Moving an existing drain or manhole that is in the way of new work, such as an extension. It adds cost, and a public sewer can also need the water company’s agreement (see build-over agreement).

A metal rod driven into the ground outside to give the house its electrical earth, where the electricity supply doesn’t provide one.

The cables that connect your electrics, and the metal water and gas pipes where they enter the house, to the main earth, so that a fault trips the power instead of making metalwork live.

The lower edge of a roof, where it meets or overhangs the top of the wall.

An electrician’s report on the condition of your existing wiring, listing anything dangerous or that needs attention. It is worth getting before you buy or renovate an older home, because it tells you whether the wiring can stay. Each problem gets a code: see EICR codes.

The codes on an EICR for each problem found. C1: danger present, with a risk of injury, so it needs making safe straight away. C2: potentially dangerous, so it needs putting right. FI: further investigation needed without delay. C3: improvement recommended, but not required. Any C1 or C2 means the report says the wiring is unsatisfactory for continued use; a report with only C3 codes is satisfactory.

Source: GOV.UK.

The certificate an electrician gives you for new wiring or a new circuit, confirming it was designed, installed and tested to the wiring regulations. Building control needs it before it can sign off the whole job. Keep it for when you sell.

Source: Richmond Council; the wiring regulations are BS 7671.

The company that runs the power cables in your area and the cable into your home: not the supplier you pay for electricity. Heat pumps and electric car chargers at home must be registered with the network operator. A heat pump installer does this for you, and for a bigger installation asks before connecting it, in case your supply needs an upgrade.

Sources: GOV.UK; MCS.

Flooring made of a thin top layer of real wood glued onto layers of plywood or other board, so from above it looks like a solid wood floor.

The outer shell of a building: walls, roof, windows, doors and ground floor, which keep the weather out and the heat in.

The work done while walls and floors are still open: running new cables, pipes and heating pipework before plastering.

The area of ground a building covers, measured on the outside of its walls.

A way of getting building regulations approval in England and Wales where building control checks your drawings before work starts. A decision usually comes within 5 weeks, or 2 months if you agree. It is the most thorough route and suits extensions and loft conversions.

Scotland: There is no full plans application in Scotland. You apply to the council for a building warrant, with drawings, and you must have it before work starts. (mygov.scot)

Source: GOV.UK.

Another name for a consumer unit. Older ones have fuses that hold a thin wire; new ones have switches and RCBO or RCD protection.

Waste pipes that slope down to the drain or soil stack, so water and waste run away on their own with no pump. If the drain is too far away or too high for that, a pump or macerator is needed instead.

Everything done in the ground before the walls go up: digging out, foundations, drains and the base of the floor. Costs can change once the ground is opened, so they are often a provisional sum.

A loft conversion where the sloping end of a hipped roof is built up into an upright end wall (a gable), so the loft gets much more headroom. It is often combined with a rear dormer. On a detached house both ends can be done: a double hip-to-gable.

A roof that slopes down on every side, including the ends, so the house has no upright end walls in the roof.

The planning application for changes to a single house (not a flat), such as an extension or work in the garden. Flats, more than one house and a change of use need a full planning application instead.

Source: Planning Portal.

The beams, usually timber, laid side by side to hold up a floor or a flat ceiling. A loft conversion needs new, stronger floor joists.

Two dormers joined at a corner: one on the main roof and one on the roof of the back addition (the outrigger), common on terraced houses and also used on semis with a back addition. Estiquote prices it as a loft type of its own, above a rear dormer of the same floor area, because of the second dormer roof and the extra steel.

Built with a slight slope so water runs away to a drain or gutter instead of sitting in puddles. Wet room floors and flat roofs are laid to fall.

A certificate from your council confirming that work you plan (or have done) doesn’t need planning permission. It isn’t compulsory for any house, a semi included: if your loft or extension is within permitted development, you can build without one. It gives you proof in writing, which helps when you sell. Used in England and Wales.

Source: Planning Portal.

A doorway or shower with no step or lip to get over, so a wheelchair, walking frame or anyone unsteady can get in easily.

A business run by two or more members, registered at Companies House like a company. Its members aren’t personally liable for debts the business can’t pay. Some architects, surveyors and building firms are LLPs.

Source: GOV.UK.

In Scotland, a panel of at least three councillors that looks again at a planning decision made by a council officer, if you ask within 3 months of the decision.

Source: SSI 2013/157, regulations 7 and 9.

A small pump fitted behind a toilet (and sometimes a basin or shower) that breaks up the waste and pumps it through a narrow pipe. It is used where the waste can’t run downhill to the soil stack.

Smoke and heat alarms wired into the mains electricity, with a battery backup, and linked so that when one goes off they all do.

Repairing the walls, floors and ceilings around new work so they are ready to decorate: filling holes, patching plaster and refitting skirting boards. Ask each builder whether it is in the price, because quotes often differ here.

A loft conversion that replaces a roof slope with a very steep, almost upright wall and a nearly flat top, with windows set into it. It gives the most space and usually needs planning permission.

The Microgeneration Certification Scheme, which certifies installers of heat pumps and other low-carbon heating. For the Boiler Upgrade Scheme grant you get quotes from MCS certified installers, and the installer applies for you.

Source: GOV.UK.

Only for people whose income, and sometimes savings, are below a set level. A grant that isn’t means tested is open to anyone who meets its other conditions.

The shorter certificate an electrician gives for small changes that don’t add a new circuit, such as an extra socket on an existing one.

Source: Richmond Council.

A price range worked out from Estiquote’s cost model, which is built from published UK cost guides and our own research, not from a quote for your home. Use it to plan and to ask questions, not as proof that a quote is wrong.

Read more: How Estiquote estimates work.

Work that must be reported to building control, or self-certified by an installer in a competent person scheme. In England and Wales notifiable electrical work includes a new circuit, a new consumer unit and changes to circuits in a room with a bath or shower. In Wales, work in kitchens and outdoors is also notifiable, even adding a socket or a light.

Sources: Hammersmith and Fulham Council, Planning Portal, Welsh Government.

Measuring a space by walking it in long, even strides and counting them. One long stride is roughly a metre, so 6 strides is about 6 m. It is close enough for a first price; use a tape measure before you ask for quotes.

The part of the building regulations in England and Wales that covers electrical safety in homes. Its guidance, Approved Document P, says which electrical work is notifiable, meaning it must be reported to building control or self-certified by an electrician in a competent person scheme. The work itself should follow BS 7671, the wiring regulations.

Sources: GOV.UK, Welsh Government.

A wall shared with your neighbour, such as the wall between two semi-detached or terraced houses. In England and Wales the Party Wall etc. Act 1996 says you must give your neighbour written notice before working on it, building on the boundary or digging foundations close to their home. If they don’t agree in writing within 14 days, a surveyor (one agreed by both of you, or one each) settles the details in a party wall award, which also decides who pays the surveyors.

Scotland: The Party Wall etc. Act 1996 does not apply in Scotland (the Act says where it applies), so there is no surveyor’s award to fall back on. Don’t start work on a shared wall without your neighbour’s written agreement. If they say no, ask a solicitor who handles property to read your title deeds and theirs and tell you what you may do to the wall, and ask your designer whether the new work can stand inside your boundary instead. If you still can’t agree, a mediation service can help you both reach an agreement. Solicitors and mediation can cost money; legal aid may help if you can’t afford it (mygov.scot).

Sources: section 5, section 10, GOV.UK.

An allowance in a quote for something you choose later, such as the kitchen units or tiles. If you choose something dearer than the allowance, you pay the difference.

Building work you can do without applying for planning permission, because the law already allows it within set limits on size, height and position. The limits differ in England, Wales, Scotland and Northern Ireland, and are tighter in a conservation area or where the council has removed some of them for your area.

Source: Planning Portal, England.

The costs of running the site rather than building anything: scaffolding, skips, a site toilet and welfare, supervision, insurance and protecting your home. Some builders list them as one line, some spread them through the price.

Read more: What preliminaries cover.

In England, a way to build a bigger single-storey rear extension than permitted development normally allows (up to 6 m deep on a semi or terrace, 8 m on a detached house) without a full planning application. You tell the council first; it writes to your neighbours, who have at least 21 days to object, and you can build if the council agrees or hasn’t decided within 42 days. It isn’t available in a conservation area.

Sources: Planning Portal, GPDO 2015, Schedule 2, Part 1, Class A, paragraph A.4.

The builder’s timetable: what happens when, and how long each stage takes. A very tight programme can mean extra labour or rushed work, so ask how it was set.

An amount a builder puts in a quote for work they can’t price yet, such as foundations before the ground has been dug. The final bill goes up or down with the real cost, so ask how each figure was worked out.

An RCD and a circuit breaker in one, fitted for each circuit, so a fault on one circuit switches off only that circuit.

A safety switch that cuts the power within a split second if electricity leaks to earth, for example through a person. One RCD often protects several circuits at once.

A private inspector you can choose instead of the council to check building work against the building regulations in England and Wales. They tell your council about the work for you. Their fee isn’t published like a council’s: they agree it with you, so ask for a quote and compare it with the council’s charge. Until 6 April 2024 they were called approved inspectors.

Sources: SI 2024/104 for England, SI 2024/207 for Wales.

A boiler that heats a hot water cylinder fed by a cold water tank in the loft, usually with a second, smaller tank in the loft for the heating. Also called a conventional or heat-only boiler. The pump and controls are separate from the boiler. Compare a system boiler, which has no tank in the loft, and a combi boiler, which has no cylinder either.

A glazed box set on a flat roof, usually with a glass roof of its own, to let daylight into the room below. It costs more than a flat rooflight.

A window set into a roof slope or a flat roof, lying flat or almost flat with it. Cheaper and simpler than a dormer or a roof lantern.

The work done after plastering: fitting sockets, switches, lights, radiators, taps and toilets, then connecting and testing them.

The toilet, hand washing, shelter and somewhere to eat that a builder must provide for the people working on site. It is part of the preliminaries.

A thin new coat of plaster spread over a whole wall or ceiling to give a smooth surface. After a rewire, the grooves cut for cables are filled and patched; if the old plaster is in poor condition, a plasterer may need to skim the whole room (a full skim), which costs more.

The large upright waste pipe, inside the house or on an outside wall, that takes waste from toilets down to the drains. The further a new toilet is from it, the more the pipework costs.

Someone who runs a business on their own account, not as a company. They make the decisions, keep the profits after tax and are personally responsible for all the business’s debts. A sole trader isn’t registered at Companies House, because they aren’t a company.

Source: GOV.UK.

A suspended floor is wooden boards on joists, with a space underneath; a solid floor is concrete laid on the ground. It matters for a rewire: under floorboards, an electrician can lift a few boards and run new cables through the space below, but a concrete floor can’t be lifted, so the cables have to go another way, usually through the walls and ceilings, which takes longer.

A written description of exactly what is to be built and with which materials and fittings. The more detailed it is, the easier builders’ quotes are to compare.

A steel beam, often called an RSJ (rolled steel joist), holds up the wall or floor above when a wall is taken out or a wide opening is made. A structural engineer works out its size, and a wider opening needs a bigger beam.

An engineer who works out how the building will stand up: the size of steel beams, lintels, joists and foundations. Their calculations go to building control with the drawings. Most extensions, loft conversions and knock-throughs need one.

Scotland: In Scotland, an engineer registered as an approved certifier of design can certify that the structure meets Scotland’s building standards. The council must accept that certificate instead of checking the structure in detail, and the building warrant fee is a little lower. (Scottish Government procedural handbook, sections 3.3.6 and 3.14.7)

A wall made of a timber or metal frame covered with plasterboard. It divides rooms but doesn’t usually hold anything up.

A surge protection device (SPD) in the consumer unit that protects the wiring and anything plugged in from brief spikes in voltage, for example from a lightning strike nearby.

In England and Wales, the written decision a party wall surveyor makes when a neighbour hasn’t agreed in writing to work under the Party Wall etc. Act 1996. It is made by one surveyor both of you agree on, or by two of the three surveyors (one each, and a third they choose), and it sets out whether and how the work can be done, when, and who pays the surveyors’ costs. Either of you can appeal to the county court within 14 days of receiving it.

Scotland: There is no surveyor’s award in Scotland, because the Party Wall etc. Act 1996 does not apply there (the Act says where it applies). See party wall for what to do instead.

Sources: section 10, GOV.UK.

A boiler that heats a hot water cylinder, usually in an airing cupboard, with the pump and controls built in and no tank in the loft. With an unvented cylinder it suits homes where two showers may run at once.

Waterproofing a floor and the lower walls, for example in a wet room or a cellar, so water can’t get through to the structure.

A shower with a valve that keeps the water at the temperature you set, even when someone turns on a tap elsewhere in the house.

The documents that show who owns a property and any rights or restrictions on it. In England and Wales most are held by HM Land Registry as a title register and a title plan, which gives an idea of where the boundaries run but usually not the exact line; in Scotland by Registers of Scotland.

Sources: GOV.UK, property boundaries.

Small holes dug before work starts to see what the ground is like, how deep the foundations need to go, or where existing foundations and drains are.

A hot water cylinder fed straight from the cold water mains, with no tank in the loft, so taps and showers get mains pressure. Because the water is stored under pressure, it must be fitted by a qualified installer and the work comes under the building regulations.

Source: East Lindsey District Council.

A hard plastic (unplasticised PVC) used for most window frames, doors, fascias and gutters. It is usually cheaper than timber or aluminium.

Value added tax. A VAT-registered builder adds 20% to most work on an existing home; a trader who isn’t registered charges none on their labour. Some work is charged less: building a new home is zero rated, so is fitting heat pumps, solar panels, batteries and insulation in a home until 31 March 2027, and renovating a home that has been empty for 2 years or more can be 5%. Always check whether a quote includes VAT before you compare it.

Sources: HMRC VAT Notice 708, VAT Notice 708/6.

A length of timber fixed along the top of a wall that the roof rafters or ceiling joists sit on.

A bathroom with an open shower on a floor that is laid to fall to a drain, with the whole floor and the lower walls waterproofed (tanked). It usually has level access.

Zero rated means no VAT: the rate is 0%. Building a new home is zero rated, and so is fitting a heat pump or insulation in a home until 31 March 2027. Building or adapting a bathroom, washroom or toilet to suit the condition of a disabled person, in their own home, can be zero rated too. Age alone doesn’t qualify: what counts is a long-term illness or disability that makes everyday activities hard, such as using the stairs, and you don’t need to be registered as disabled.

Sources: VAT Notice 708, VAT Notice 708/6, VAT Notice 701/7, sections 3.1, 3.2.1 and 6.3.